Recently, there is a tendency for services based on the social networks in communication devices to rapidly increase. The social network refers to a network that is comprised of a user and other users who are related to the user's interests or activities. Services, which use the social networks, rapidly spread in order to: meet expression desires of individuals; share information with other users; and establish a relationship with other users.
However, since conventional social network services provide a function of merely transmitting and receiving data based on the network that is formed between user terminals, the services have limitations in satisfying the user's desire for various services to be provided.